As part of Android Pay’s arrival in the UK, Google introduced a partnership with Transport for London that will allow riders to use the app’s NFC technology for transit fares. While some cities have been testing mobile NFC ticketing, London’s a leader with system-wide mobile payments apps. (TfL riders can already use Apple Pay and Samsung Pay.)

Using actual TfL ticket barriers onstage, senior director of product development Pali Bhat showed how riders simply tap in and out of turnstiles with their phones, with the fare deducted automatically from their bank or credit card on file.

Besides the ultimate convenience of not having to juggle a card or constantly add value, Android Pay is able to charge passengers more accurately for where they actually travelled. For routes that charge per journey or zone based on distance, Android Pay is smart enough to calculate the rate depending on when riders tap in and out. And although this is not a problem for some transit systems, in London if you don’t “tap out” at the end of your journey, you get charged the maximum fare. Android Pay lets you tap out remotely.

Besides making transit transactions painless for passengers, there are a slew of advantages for this type of payment on the transportation agency side. The system won’t need to install or maintain as many expensive ticketing kiosks, keeping infrastructural costs down. And TfL will be able to collect a ton of very nuanced data about ridership this way, which will almost certainly lead to more efficient service. Down the road, the technology could eventually be universal, so passengers wouldn’t ever have to worry about learning the ticketing systems in every city they visit.